With the development of communication technology, mobile communications have made a great leap forward from voice services to mobile broadband data services, which not only greatly changes people's life style but also significantly promotes the development of society and economy. As two major driving forces for the future development of mobile communications, mobile Internet and Internet of Things enable a wide range of applications of the Fifth Generation (5G) technology. Towards 2020 and beyond, data traffic will increase by several thousand times, and connections among hundreds of billions of devices and diverse service requirements will pose serious challenges to the 5G system design. The 5G technology will satisfy people's very high requirements for traffic density, number of connections and mobility, and can provide users with extreme service experiences such as high fidelity video, virtual reality, augmented reality, cloud desktop and online games. The 5G technology will penetrate into fields such as Internet of Things to be deeply integrated with industrial facilities, medical devices, vehicles and the like, so as to completely realize “Internet of Everything” and effectively satisfy requirements for information services in vertical industries such as industry, medical treatment and transportation. Further, the 5G technology will significantly improve energy and cost efficiency of network construction and operation, promote service innovation capability comprehensively, and enlarge the scope of the mobile communications industry.
However, in a conventional Long Term Evolution (LTE) network, if a UE in a Radio Resource Control (RRC) connection state needs to change its serving cell during its movement, handover has to be conducted, which results in a large amount of air interface signaling and core network side signaling.